By default the Yoast SEO plugin will output a canonical tag for every page/post on your site, and will use the permalink of that page/post for the canonical URL value.
Normally, you would leave the Canonical URL blank by default and the canonical tag will automatically be set to the same value as the page’s permalink. The Canonical tag is used to avoid duplicate content issues when you have the same content available on many variations of a URL, so that all those various URLs can all point to one URL for indexing purposes. We also have additional information on this feature at the following link: https://kb.yoast.com/kb/canonical-urls-in-wordpress-seo/
If you do wish to change the Canonical URL for a page, you would need to perform the following steps:
Go to the ‘Edit’ screen for a page/post
Scroll down to the Yoast SEO box and click on the ‘Advanced’ tab.
Set a value set for the Canonical URL
Click ‘Update’
We also have additional information on using the canonical tag and in what situations to implement it at the following link: https://yoast.com/rel-canonical/.
As for the warning that some of your pages have a ‘nofollow’ tag, Whether you choose to set a page to nofollow depends on the nature of the links on that page. Google roughly indicates that there are three reasons to nofollow links:
Untrusted content
Paid links
Crawl prioritization
Comments are an example of an area of content where you would typically not want the links to be followed, as they typically will have links that contain the first two types. We also have more information on what types of pages you may want to set to noindex/nofollow at the following link: https://yoast.com/which-pages-noindex-or-nofollow/
You can select whether a page is set to ‘nofollow’ by performing the following steps:
Go to the Edit screen for a page/post
Scroll down to the Yoast Metabox
Click on the ‘Advanced’ tab
For ‘Should search engines follow links on this Page?’ select ‘Yes’ or ‘No’
Click Update
We also have a guide on how to set a page/post to nofollow or noindex here: https://kb.yoast.com/kb/how-do-i-noindex-urls/
Setting this to resolved.
